Measurement of the ratio B(t → Wb)/B(t → Wq) in pp collisions at √s = 8 TeV
Author(s)Apyan, Aram; Barbieri, Richard Alexander; Bauer, Gerry P; Busza, Wit; Cali, Ivan Amos; Chan, Matthew Hans; Di Matteo, Leonardo; Dutta, Valentina; Gomez-Ceballos, Guillelmo; Goncharov, Maxim; Gulhan, Doga Can; Klute, Markus; Lai, Yue Shi; Lee, Yen-Jie; Levin, Andrew Michael; Luckey Jr, P David; Ma, Teng; Paus, Christoph M. E.; Ralph, Duncan Kelley; Roland, Christof E; Roland, Gunther M; Stephans, George S. F.; Stoeckli, Fabian; Sumorok, Konstanty C; Velicanu, Dragos Alexandru; Veverka, Jan; Wyslouch, Boleslaw; Yang, Mingming; Zanetti, Marco; Wyslouch, Victoria; ... Show more Show less
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The ratio of the top-quark branching fractions R=B(t→Wb)/B(t→Wq), where the denominator includes the sum over all down-type quarks (q=b,s,d), is measured in the t[¯ overt] dilepton final state with proton–proton collision data at √s=8 TeV from an integrated luminosity of 19.7 fb[superscript −1], collected with the CMS detector. In order to quantify the purity of the signal sample, the cross section is measured by fitting the observed jet multiplicity, thereby constraining the signal and background contributions. By counting the number of b jets per event, an unconstrained value of R=1.014±0.003(stat.)±0.032(syst.) is measured, in a good agreement with current precision measurements in electroweak and flavour sectors. A lower limit R > 0.955 at the 95% confidence level is obtained after requiring R≤1, and a lower limit on the Cabibbo–Kobayashi–Maskawa matrix element |V[subscript tb] | > 0.975 is set at 95% confidence level. The result is combined with a previous CMS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, Γ[subscript t] =1.36±0.02(stat.) −0.11 +0.14 (syst.) GeV.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physics Letters B
Khachatryan, V., et al. “Measurement of the Ratio B (t → Wb/B (t → Wq) in Pp Collisions at √s = 8 TeV.” Physics Letters B, vol. 736, Sept. 2014, pp. 33–57. © 2014 The Authors
Final published version